Control apparatus for hybrid vehicle

ABSTRACT

An FI/AT/MGECU, in a cylinders deactivation operating state during cruise control where the vehicle speed follows a predetermined target speed, regulates renewal on an addition side of a power plant required torque final value TQPPRQF, and in a case where a flag value of a torque hold flag F_CCKTQS showing to hold the power plant required torque final value TQPPRQF to a predetermined torque value related to a cylinder deactivation upper limit torque TQACS is a “1” (YES side in step S 33 ), when the vehicle speed VP is decreased less than a value obtained by subtracting from a set vehicle speed VC which it the target vehicle speed during cruise control, a predetermined vehicle speed #ΔV (for example, #ΔV=3 km/h or the like) (YES side in step S 35 ), the internal-combustion engine E is switched from a cylinders deactivation operation to an all cylinders operation. The fuel consumption efficiency is thus improved while keeping occupants in the vehicle from feeling discomfort with respect to travelling behavior.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a control apparatus for a hybridvehicle which is mounted in a hybrid vehicle propulsion driven byjointly using an internal-combustion engine and a motor, and wherein thedriving force from at least one of the internal-combustion engine andthe motor is transmitted to the driving wheels.

Priority is claimed on Japanese Patent Application No. 2003-192315,filed Jul. 4, 2003, and No. 2003-403211, filed Dec. 2, 2003, thecontents of which are incorporated herein by reference.

2. Description of Related Art

Conventionally, for example, in a hybrid vehicle which comprises aninternal-combustion engine and a motor as a power source and whichtransmits the driving force from at least one of the internal-combustionengine and the motor to the driving wheels for traveling, a controlapparatus for a hybrid vehicle has been well known which sets an enginetorque required by the internal-combustion engine and a motor torquerequired by the motor according to the operating state of the vehicle.

In such a control apparatus for a hybrid vehicle, for example a controlapparatus comprising a constant speed drive unit which drives a vehicleto travel so that the speed of the vehicle (vehicle speed) detected by avehicle speed sensor follows a target vehicle speed which is a targetvalue of the vehicle speed, has been known. Regarding this constantspeed drive unit, the arrangement is such that, if a speed difference isgenerated between the vehicle speed detected and the target speed, atorque output from the internal-combustion engine and the motor isincreased or decreased so as to counteract this speed difference (forexample, Japanese Patent Application Unexamined Publication No. Hei9-207622).

Incidentally, in a hybrid vehicle according to an example of the aboveconventional technique, for example, in the case where this comprises avariable cylinder internal-combustion engine capable of switchingbetween an all cylinders operation which operates all cylinders and apartial cylinders deactivation operation which operates with somecylinders deactivated (cylinders deactivation operation) as aninternal-combustion engine having high fuel consumption efficiency, andthis is set in order to switch the all cylinders operation and thecylinders deactivation operation according to the operating state of thevehicle, then in a state where the vehicle is driven to travel so thatthe detected vehicle speed becomes the target vehicle speed, by simplyincreasing and decreasing only the torque from the internal-combustionengine and the motor so as to counteract the speed difference betweenthe detected vehicle speed and the target vehicle speed, there is alikelihood that hunting which frequently switches between the allcylinders operation and the cylinders deactivation operation, occurs sothat occupants in the vehicle may feel discomfort with respect totravelling behavior.

Moreover, in the control apparatus for a hybrid vehicle comprising sucha variable cylinder internal-combustion engine, it is desired to improvethe fuel consumption efficiency by enlarging the region which continuesthe cylinders deactivation operation with respect to, for example anamount of a vehicle state such as the accelerator pedal opening or thevehicle speed.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above situation, andit is an object thereof to provide a control apparatus for a hybridvehicle in which fuel consumption efficiency can be improved whilekeeping occupants in the vehicle from feeling discomfort with respect totravelling behavior.

In order to solve the above problem and achieve the related object,according to the present invention there is provided a control apparatusfor a hybrid vehicle which comprises: a variable cylinderinternal-combustion engine capable of switching between an all cylindersoperation which operates all cylinders and a cylinders deactivationoperation which operates with some cylinders deactivated, and a motor asa power source; and a power storage unit which transfers electric energywith the motor (for example, the battery 3 in the embodiment), and atleast one of the variable cylinder internal-combustion engine and themotor is connected to driving wheels of the vehicle through atransmission so as to transmit a driving force to the driving wheels,wherein the control apparatus comprises: a fuel supply canceling device(for example, the cylinders deactivation controlling section 59 in theembodiment) which cancels fuel supply to the aforementioned somecylinders according to an operating state of the vehicle; a cruisecontrol device (for example, the C/C (cruise control) unit 53 in theembodiment) which controls at least one of a cruise control to traveldrive the vehicle so that the vehicle speed (for example, the vehiclespeed VP in the embodiment) follows a predetermined target speed (forexample, the set vehicle speed VC in the embodiment), and a cruisecontrol to make the vehicle travel while maintaining a predeterminedvehicular gap with respect to a preceding vehicle; an upper limit enginetorque calculating device (for example, step S09 in the embodiment)which calculates an upper limit value of an engine torque capable ofbeing output from the variable cylinder internal-combustion engineduring the cylinders deactivation operation (for example, the cylinderdeactivation upper limit ENG torque TQCS in the embodiment); an upperlimit motor torque calculating device (for example, step S10 in theembodiment) which calculates an upper limit value of motor torquecapable of being output from the motor during an assisting operationwhich assists the output of the variable cylinders internal-combustionengine by the output from the motor (for example, the energy managementdischarge torque limit for cylinder deactivation enlargement assistanceTQMLTCSA in the embodiment); a torque limiting device (for example, stepS19 in the embodiment) which limits a target torque for a power planttorque capable of being output from a power plant comprising thevariable cylinder internal-combustion engine and the motor duringoperation of the fuel supply canceling device and the cruise control(for example, the power plant required torque final value TQPPRQF in theembodiment) to under a value equivalent to a predetermined torquerelated to a cylinder deactivation upper limit torque obtained by addingan upper limit value of the engine torque and an upper limit value ofthe motor torque; and a fuel supply cancel releasing device (forexample, step S32 in the embodiment) which releases cancellation of thefuel supply to at least some of the cylinders among the cylinders towhich the fuel supply is cancelled by the fuel supply canceling device,when the vehicle speed is decreased under a speed obtained bysubtracting from the target speed, a predetermined speed (for example,the predetermined vehicle speed #ΔV in the embodiment) during operationof the torque limiting device.

According to the control apparatus for a hybrid vehicle having the aboveconstruction, the upper limit motor torque calculating device calculatesthe upper limit value of the motor torque capable of being output fromthe motor during the assisting operation, for example according to anenergy state in high voltage electrical equipment constituting the powerstorage unit. Moreover, in the cylinders deactivation operating stateduring cruise control, in the case where the target torque for the powerplant torque is increased, for example exceeding the cylinderdeactivation upper limit torque obtained by the upper limit value of theengine torque and the upper limit value of the motor torque, the torquelimiting device regulates renewal on the addition side of this targettorque, and limits the target torque to under a value equivalent to thepredetermined torque related to the cylinder deactivation upper limittorque. Furthermore, in the case where the vehicle speed is more than aspeed obtained by subtracting from the target speed, a predeterminedspeed, the state which regulates the renewal on the addition side of thetarget torque is continued. In the case where the vehicle speed isdecreased below a speed obtained by subtracting from the target speed, apredetermined speed, the fuel supply is started with respect to at leastsome of the cylinders among the cylinders in the deactivated state. Thatis, even in the case where the target torque for the power plant torqueexceeds for example the cylinder deactivation upper limit torque, byallowing deceleration to a level where occupants in the vehicle can notfeel discomfort, the cylinders deactivation operation can be continuedand the timing for switching from the cylinders deactivation operationto the all cylinders operation can be delayed, so that fuel consumptionefficiency can be improved.

Preferably, in the control apparatus for a hybrid vehicle having theabove construction, the fuel supply cancel releasing device cancels theoperation of the fuel supply canceling device to thereby switch theoperating state of the variable cylinder internal-combustion engine fromthe cylinders deactivation operation to the all cylinders operation.

According to the control apparatus for a hybrid vehicle, even in thecase where, accompanying the decrease in the vehicle speed due to theoperation of the torque limiting device to under the speed obtained bysubtracting from the target speed, the predetermined speed, for examplethe driver of the vehicle instructs to accelerate by operation of theaccelerator pedal, it is possible to generate a driving force unerringlyreflecting the driver's intention to accelerate at an appropriatetiming.

Preferably, in the control apparatus for a hybrid vehicle having theabove construction the fuel supply canceling device, in at least onecase of: a case where the air/fuel ratio of an air-fuel mixture suppliedto the variable cylinder internal-combustion engine is changed from atheoretical air/fuel ratio to a rich side state; a case where a shiftoperation is executed in the transmission; a case where a temperature ofa catalyst which purifies exhaust gas of the variable cylinderinternal-combustion engine departs from a predetermined activationtemperature range; a case where a duration of the cylinders deactivationoperation exceeds a predetermined duration; and a case where a rotatingspeed of the variable cylinder internal-combustion engine is decreasedto under a predetermined rotating speed, releases the cancellation ofthe fuel supply to at least some of the cylinders among the cylinders towhich the fuel supply is cancelled by the fuel supply canceling device.

According to the control apparatus for a hybrid vehicle, it is possibleto control the operating state of the internal-combustion engineappropriately and flexibly according to the state of the vehicle.

Preferably, the control apparatus for a hybrid vehicle having the aboveconstruction further comprises: a fuel supply cancel prohibiting device(for example, the FI/AT/MGECU 36 in the embodiment) which, after thefuel supply cancel releasing device releases the cancellation of thefuel supply to at least some of the cylinders among the cylinders towhich the fuel supply is cancelled by the fuel supply canceling device,prohibits execution of the cancellation of fuel supply to the at leastsome of the cylinders to which the cancellation of the fuel supply isreleased by the fuel supply cancel releasing device.

Furthermore, according to the control apparatus for a hybrid vehicle, itis possible to suppress the occurrence of hunting where canceling andreleasing of canceling of the fuel supply is alternatively repeated, andit is possible to keep occupants in the vehicle from feeling discomfortwith respect to the traveling behavior.

Preferably, in the control apparatus for a hybrid vehicle having theabove construction, the upper limit value of motor torque is calculatedaccording to a state of charge of the power storage unit.

According to the control apparatus for a hybrid vehicle, it is possibleto appropriately continue processing of the cylinder deactivationenlargement assistance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a construction of a control apparatus for a hybrid vehicleaccording to an embodiment of the present invention.

FIG. 2 is a block diagram of the control unit shown in FIG. 1.

FIG. 3 is a flowchart showing a processing which sets a torque hold flagF_CCKTQS.

FIG. 4 is a flowchart showing a processing which sets the torque holdflag F_CCKTQS.

FIG. 5 is a flowchart showing a processing of a cylinders deactivationcontrol based on the torque hold flag F_CCKTQS.

FIG. 6 is a graph showing an example of change with time during cruisecontrol of: vehicle speed VP, power plant required torque final valueTQPPRQF, a flag value of an FI all cylinders determination flag, a flagvalue of a CC all cylinders required flag, an actual operating state ofthe internal-combustion engine E, and a gradient of a vehicle path.

FIG. 7 is a flowchart showing a processing which sets the torque holdflag F_CCKTQS according to a modified example of an embodiment of thepresent invention.

FIG. 8 is a graph according to a modified example of an embodiment ofthe present invention, showing the change with time during cruisecontrol of; the vehicle speed VP, the power plant required torque finalvalue TQPPRQF, the flag value of the FI all cylinders determinationflag, the flag value of the CC all cylinders required flag, the actualoperating state of the internal-combustion engine E, and the gradient ofthe vehicle path track.

FIG. 9 is a flowchart showing a processing of a cylinders deactivationcontrol according to a modified example of an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Hereunder is a description of a control apparatus for a hybrid vehicleaccording to an embodiment of the present invention with reference tothe appended drawings.

FIG. 1 shows a parallel hybrid vehicle according to the embodiment ofthis invention having a construction where an internal-combustion engineE, a motor M, and a transmission T are connected directly in series. Thedriving force of both the internal-combustion engine E and the motor Mis transmitted, for example, from the transmission T such as anautomatic transmission (AT) or manual transmission (MT), to the drivingwheels W of the vehicle, via a differential gear (not shown) whichdistributes the driving force between driving wheels W on the right andthe left (front wheels or rear wheels). Moreover, when a driving forceis transmitted from the driving wheel W side to the motor M side at thetime of deceleration of the hybrid vehicle, the motor M functions as agenerator to generate so-called regenerative braking, and the kineticenergy of the vehicle body is recovered as electrical energy.

The motor M, being for example a three-phase brushless DC motor or thelike, is connected to a power drive unit (PDU) 2. The power drive unit 2comprises, for example a PWM inverter involving pulse width modulation(PWM), installed with a bridge circuit being a bridge connected using aplurality of transistor switching elements, and is connected to anickel-hydrogen battery (battery) 3 of a high voltage system whichtransfers the power for the motor M (the power supply which is suppliedto the motor M during the power running operation (driving or assisting)of the motor M, or the regenerated power which is output from the motorM during the regenerative operation).

Moreover, the drive and regenerative operation are performed by thepower drive unit 2 receiving control instructions from a control unit 1.That is, for example when driving the motor M, based on torqueinstructions input from the control unit 1, the power drive unit 2converts the DC power output from the battery 3 into three-phase ACpower and supplies this to the motor M. On the other hand, during theregenerative operation of the motor M, the three-phase AC power outputfrom the motor M is converted into the DC power and the battery 3 ischarged.

Furthermore, an auxiliary battery 4 of 12 volts for driving variousaccessories, is connected to the power drive unit 2 and the battery 3 inparallel via a downverter 5 which is a DC-DC converter. The downverter 5is controlled by the control unit 1 and charges the auxiliary battery 4by lowering the voltage of the power drive unit 2 or the battery 3.

Moreover, a crankshaft of the internal-combustion engine E is connected,for example through a belt or a clutch to a rotation shaft of an airconditioning motor (not shown) equipped in a hybrid air conditioningcompressor (HBAC) 6. This air conditioning motor is connected to an airconditioning inverter (HBAC INV) 7. The air conditioning inverter 7 isconnected in parallel to the power drive unit 2 and the battery 3, andunder the control of the control unit 1, converts the DC power outputfrom the power drive unit 2 and the battery 3 into three-phase AC powerto supply to the air conditioning motor so as to drive control thehybrid air conditioning compressor 6.

That is, in the hybrid air conditioning compressor 6, the driving load,for example the discharge of the refrigerant, is variably controlledunder the driving force from at least one of the internal-combustionengine E and the air conditioning motor during the power runningoperation of the air conditioning motor. Here, “hybrid” in the hybridair conditioning compressor 6 means that it can be driven by either oneof the internal-combustion engine E and the motor M.

Between the internal-combustion engine E and the air conditioning motor,there are for example, a crankshaft pulley integrally provided with thecrankshaft of the internal-combustion engine E, a driving shaft pulleypaired with the crankshaft pulley and integrally provided with a drivingshaft connectable with the rotation shaft of the air conditioning motorthrough a clutch, and a belt spanning between the crankshaft pulley andthe driving shaft pulley.

That is, between the crankshaft pulley and the driving shaft pulley, thedriving force is transmitted through the belt.

Moreover, the internal-combustion engine E is a so-called SOHC V6cylinder engine, of a construction having three cylinders on one bankcomprising a variable valve timing mechanism VT enabling a cylinderdeactivation operation, and a construction having three cylinders on theother bank comprising a normal valve operating mechanism (not shown)which does not perform the cylinder deactivation operation. Furthermore,the three cylinders enabling the cylinder deactivation operation have aconstruction such that respective two inlet valves and two exhaustvalves are able to maintain the closed state by means of the variabletiming mechanism VT, via an oil pressure pump 11, a spool valve 12, acylinder deactivation side path 13, and a cylinder deactivationcancellation side path 14.

That is, the internal-combustion engine E may be switched between threecylinders operation (cylinder deactivation operation) in the state suchthat the three cylinders on one side bank are deactivated, and sixcylinders operation (all cylinders operation) such that all sixcylinders on both side banks are driven.

Specifically, if operating oil being supplied from the oil pressure pump11 through the lubrication system piping 11 a to the engine lubricationsystem is partially supplied via the spool valve 12 comprising asolenoid controlled by the control unit 1, to the cylinder deactivationside path 13 on the bank capable of cylinder deactivation operation, acam lift rocker arm 16 a (16 b) and valve drive rocker arms 17 a (17 b)which are supported on the respective rocker shafts 15 and wereintegrally driven, are able to be driven separately. Therefore, thedriving forces of the cam lift rocker arms 16 a and 16 b driven by therotation of the cam shaft 18 are not transmitted to the valve driverocker arms 17 a and 17 b, so that the inlet valves and the exhaustvalves remain in the closed state. Accordingly the cylinder deactivationoperation where the inlet valves and the exhaust valves of the threecylinders become in the closed state may be performed.

The internal-combustion engine E is mounted via a damping device (ACM:Active Control Engine Mount) 19 onto the vehicle so that the dampingdevice 19 can suppress the generation of vehicle vibration accompaniedwith the operating state of the internal-combustion engine E, that isthe switching of the three cylinders operation (cylinder deactivationoperation) and the six cylinders operation (all cylinders operation).

Moreover, this internal-combustion engine E comprises an electronicthrottle control system (ETCS) 20 which electronically controls athrottle valve (not shown).

The ETCS 20 drives an ETCS driver according to the throttle openingcalculated in the control unit I based for example on the acceleratorpedal opening related to the operating amount of the accelerator pedal(not shown) by a driver, the operating state of the vehicle such as thevehicle travelling speed (vehicle speed) VP or the engine speed NE, andon the torque distribution between the internal-combustion engine E andthe motor M, so as to directly control the throttle valve.

For example the transmission T being the automatic transmission (AT) isconstructed to comprise a torque converter 22 equipped with a lock-upclutch (LC) 21, and an electric oil pump 23 which generates the oilpressure for drive controlling the torque converter 22 and for theshifting operation of the transmission T.

The electric oil pump 23 is drive controlled by the control unit 1 withthe power supply from the battery 3.

The torque converter 22 transmits the torque by a spiral flow of theoperating oil (ATF: Automatic Transmission Fluid) enclosed inside. In anLC_OFF state where the engagement of the lock-up clutch 21 is cancelled,the torque is transmitted (for example, amplification transmission) fromthe rotation shaft of the motor M to the input shaft of the transmissionT via the operating oil.

Furthermore, in an LC_ON state where the lock-up clutch 21 is set up inthe engagement state, the rotation driving force is directly transmittedfrom the rotation shaft of the motor M to the input shaft of thetransmission T and not via the operating oil.

Moreover, a booster BS is linked to the brake pedal (not shown). Amaster power internal negative pressure sensor S9 which detects thebrake master power internal negative pressure is provided in the boosterBS.

Moreover, the driving wheel W comprises a brake device 24. The brakedevice 24 suppresses the generation of rapid behavioral change of thevehicle by control of the control unit 1. For example, it preventsslipping of the driving wheel W on a slippery road surface or the like,suppresses side slip such as oversteering or understeering, prevents thedriving wheel W from being in a locked state during braking, ensures thedesired driving force and the steering performance of the vehicle,stabilizes the posture of the vehicle, and assists with travelling bymeans of a creep force, for example, prevents the vehicle from movingbackward on a slope when deactivating the internal-combustion engine E.

Inputs to the control unit 1 are: for example: a detection signal from avehicle speed sensor S1 which detects the travelling speed of thevehicle VP, a detection signal from an engine speed sensor S2 whichdetects the engine speed NE, a detection signal from a shift positionsensor S3 which detects the shift position SH of the transmission T, adetection signal from a brake switch S4 which detects the operatingstate BR of the brake (Br) pedal, a detection signal from an acceleratorpedal opening sensor S5 which detects the accelerator pedal opening APaccording to the operation amount of the accelerator pedal, a detectionsignal from a throttle opening sensor S6 which detects the throttleopening TH, a detection signal from an intake pipe pressure sensor S7which detects the intake pipe pressure PB, a detection signal from abattery temperature sensor S8 which detects the temperature TBAT of thebattery 3, a detection signal from the master power internal negativepressure sensor S9, a detection signal from a POIL sensor S10 whichdetects the oil pressure of the cylinder deactivation cancellation sidepath 14 when deactivating the cylinders, a detection signal from a PDUtemperature sensor S11 which detects the temperature TPDU of the powerdrive unit 2, and a detection signal from a DV temperature sensor S12which detects the temperature TDV of the downverter 5.

Moreover, the control unit I comprises: for example: a VSA (VehicleStability Assist) ECU 31 which drive controls the brake device 24 tostabilize the behavior of the vehicle, an ACMECU 32 which drive controlsthe damping device 19 to suppress the generation of car body vibrationcaused by the operating state of the internal-combustion engine E, aMOTECU 33 which controls the driving and the regenerative operation ofthe motor M, an A/CECU 34 which drive controls the air conditioninghybrid air conditioning compressor 6 and the air conditioning inverter7, and an HVECU 35 which monitors and protects the high voltageelectrical equipment system comprising for example the power drive unit2, the battery 3, the downverter 5, and the motor M, and controls theoperation of the power drive unit 2 and the downverter 5, and aFI/AT/MGECU 36 The respective VSAECU 31 to 36 are mutually connectedcommunicably. The respective ECUs 31 to 36 are connected to a meter 37comprising instruments which display the amount of the respective typesof states.

For example, as shown in FIG. 2, the FI/AT/MGECU 36 comprises; aFI/MG-CPU 46 installed with an A/F (air/fuel ratio) control unit 41 andan IG (ignition) control unit 42 which control the fuel supply to andthe ignition timing of the internal-combustion engine E, a torquemanagement section 43, a power management section 44, and an energymanagement section 45; and for example an AT-CPU 47 which controls theshifting operation of the transmission T, the operating state of thelock-up clutch 2, and the like.

In the torque management section 43, a driver required torquecalculating section 51 calculates the torque value required by a driverof the vehicle (driver required torque) depending on the operationamount of the accelerator by the driver, for example based on respectivedetection signals from the accelerator pedal (AP) opening, the enginespeed NE, the vehicle travelling speed VP, the shift position SH, theoperating state of a brake pedal BRK_SW, and the operating state ABS ofan antilock brake system which prevents the driving wheels W from beinglocked during vehicle braking by the brake device 24, and outputs thistorque value to a first torque selecting section 52.

Moreover, a C/C (cruise control) unit 53 calculates the torque value(C/C required torque) targeted during the travel control satisfyingpredetermined traveling conditions previously set according to the inputoperation of the driver, that is cruise control, for example, such asthe constant speed travelling control which controls theinternal-combustion engine E and the motor M so that the vehicletravelling speed VP detected in a vehicle speed sensor SI becomes thetarget vehicle speed which is the target value of the travelling speedof the vehicle, and follow travel control for following a precedingvehicle while maintaining a predetermined vehicular gap, and outputs thetorque value to the first torque selecting section 52.

The first torque selecting section 52 selects the greater torque valueof the driver required torque or the C/C required torque, and outputs tothe torque switching section 54. Therefore, for example even duringcruise control, in the case where the driver required value according tothe accelerator operation of the driver of the vehicle is over the C/Crequired torque, the torque according to the driver required value isoutput.

The torque switching section 54 selects either one of the torque valueinput from the first torque selecting section 52 and the AT requiredvalue input from the AT-CPU 47, and outputs to a second torque selectingsection 55.

The AT-CPU 47 selects either one of the torque values as the AT requiredtorque among, for example; a torque value set during the shiftingoperation of the transmission T, a torque value targeted when performingsynchronizing control which synchronize the period of the input shaft ofthe transmission T and the rotating speed of the motor M during drivingthe lock-up clutch 21 or shifting the speed such as shifting down, and atorque value set during protection control of the transmission T in thecase where a driver operates the accelerator pedal and the brake pedalat the same time.

Moreover, the AT-CPU 47 electronically controls the oil pressure whichdrives the lock-up clutch 21 by an LC linear solenoid, and it ispossible to set the operation, in addition to the LC_ON state where thelock-up clutch 21 is in the engagement state and the LC_OFF state wherethe engagement is cancelled, to an intermediate state which generates anappropriate smoothness in the lock-up clutch 21.

The second torque selecting section 55 selects the smaller torque valueof the torque value input from the torque switching section 54 and theVSA required torque input from the VSAECU 31, then sets this torquevalue as a torque of the crankshaft (crankshaft torque), that is thetarget torque value with respect to the actual rotation of the drivingwheels W, and outputs to a first adding section 56.

Moreover, an auxiliary torque-ENG friction calculating section 57calculates, for example the auxiliary torque (HAC) required for drivingthe accessories based on the protrusive pressure (PD) of the airconditioner, calculates the torque value in relation to the engine (ENG)friction of the internal-combustion engine E based on the increasedamount of the engine friction in a low temperature state compared to astandard for the engine friction value after termination of warming upof the internal-combustion engine E, and outputs to the first addingsection 56.

The first adding section 56 sets the value obtained by adding the crankterminal torque and the torque value input from the auxiliary torque-ENG friction calculating section 57, as the power plant (P/P) torquewhich is the target torque for the torque output from the power plant(that is, the internal-combustion engine E and the motor M), and outputsto a torque distribution calculating section 58.

The torque distribution calculating section 58 selects the requiredtorque mode for instructing the predetermined operating state of theinternal-combustion engine E and the motor M based on the cylinderdeactivation determination output from the cylinder deactivation controlunit 59 for determining whether the cylinder deactivation operation ofthe internal-combustion engine E should be executed or not, and thelimit torque and the required torque for the motor M output from thepower management section 44, and according to the selection result, setsthe distribution of the power plant torque (P/P) with respect to therespective torque instructions of the internal-combustion engine E andthe motor M.

To the cylinder deactivation control unit 59 is input the limit torquefor the motor M output from the power management section 44 describedlater, and according to the limit torque for the motor M, the cylinderdeactivation control unit 59 determines whether the cylinderdeactivation operation should be executed or not.

The power management section 44 calculates, for example the motor (MOT)limit torque based on the smaller power of the battery (BATT) protectinglimit power output from the HVECU 35 and the charge-discharge limitpower output from the energy management section 45, then sets thesmaller one of the calculated motor limit torque and the motor (MOT)winding protecting limit torque output from the HVECU 35 as the limittorque, and outputs to the torque distribution calculating section 58and the cylinder deactivation control unit 59.

Moreover, the power management section 44 calculates, for example themotor (MOT) limit torque based on the smaller power of the battery(BATT) protecting limit power output from the HVECU 35 and the requiredcharge-discharge power output from the energy management section 45,then sets the smaller one of the calculated motor limit torque and themotor (MOT) winding protecting limit torque output from the HVECU 35 asthe required torque, and outputs to the torque distribution calculatingsection 58.

The charge-discharge limit power and the required charge-discharge poweroutput from the energy management section 45 are, for example thelimited amount and the required amount with respect to charge anddischarge set according to the state of charge of the battery 3 and theauxiliary battery 4.

Moreover, the battery (BATT) protecting limit power output from theHVECU 35 is, for example the limit value of the output power of thebattery 3 set according to the temperature state of the battery 3, theauxiliary battery 4, and the other high voltage electrical equipment.The motor (MOT) winding protecting limit torque is the limit value ofthe output torque of the motor M set according to the temperature stateof the motor M.

The torque instruction of the internal-combustion engine E calculated bythe 20 torque distribution calculating section 58 is input into asubtracting section 60. The subtracting section 60 inputs the valueobtained by subtracting the torque value input from the feedback (F/B)processing section 67 described later from the torque instruction of theinternal-combustion engine E, to a target TH calculating section 61. Thetarget TH calculating section 61 calculates the target value for theelectronic throttle opening TH in relation to the drive of the ETCSdriver based on the input torque value, and outputs to a third torqueselecting section 62.

The third torque selecting section 62 selects the greater throttleopening value of the target value of the electronic throttle opening THinput from the target TH and the idle opening output from the idlecontrol unit 63, and outputs this throttle opening value to the ETCSdriver 64.

The idle opening output from the idle control unit 63 is, for example, alimit value with respect to the throttle opening TH for preventing theengine speed NE from being less than the predetermined rotating speedduring the idle operation of the internal-combustion engine E.

Moreover, to the ENG torque calculating section 65 in the torquemanagement section 43 is input a detection signal intake air amount (orsupplied oxygen amount) of the internal-combustion engine E detected byan airflow meter (AFM) 66. The ENG torque calculating section 65calculates the ENG torque output from the internal-combustion engine Ebased on the detection value of the intake air amount, and outputs tothe feed back (F/B) processing section 67 and a second adding section68.

The feed back (F/B) processing section 67, with respect to the torqueinstruction of the internal-combustion engine E calculated in the torquedistribution calculating section 58, corrects for calculation errors ofENG torque based for example on the detection value of the airflow meter66, response characteristic or aged deterioration of theinternal-combustion engine E, performance irregularities during massproduction of the internal-combustion engine E and the like, by feedback processing, and inputs the ENG torque calculated in the ENG torquecalculating section 65 to the subtracting section 60.

A third adding section 68 inputs the torque value obtained by adding;the ENG torque calculated in the ENG torque calculating section 65, thetorque value input from the auxiliary torque-ENG friction calculatingsection 57, and the motor real torque input from the MOTECU 33, to thereal torque calculating section 69. The real torque calculating section69 calculates the real torque value which is actually output from thepower plant (that is, the internal-combustion engine E and the motor M)based on the input torque value.

To the MOTECU 33 is input the torque instruction of the motor Mcalculated by the torque distribution calculating section 58 in thetorque management section 43, via the HVECU 35. The MOTECU 33 calculatesthe motor real torque which is actually output from the motor M based onthe input torque value, and inputs to the third adding section 68 in thetorque management section 43, via the HVECU 35.

Moreover, the real torque value calculated in the real torquecalculating section 69 is input to the AT-CPU 47, and based on this realtorque value, the oil pressure which drives the lock-up clutch 21 iselectronically controlled by an LC linear solenoid.

The respective torque values calculated in the torque management section43 are corrected according to the ignition timing, the air/fuel ratio,and the presence/absence of the fuel cut (fuel supply cancellation) ofthe internal-combustion engine E which are controlled in the A/F(air/fuel ratio) control unit 41 and the IG (ignition) control unit 42.

The control apparatus for a hybrid vehicle according to the presentembodiment comprises the above construction. Next is a description of anoperation of this control apparatus for a hybrid vehicle, particularly,processing which switches the operating state of the internal-combustionengine E during cruise control, that is switches between the allcylinders operation and the cylinders deactivation operation.

Hereunder is a description of processing which sets the flag value of atorque hold flag F_CCKTQS showing whether it is possible to execute thetorque hold processing which enlarges the cylinders deactivationoperation region with respect to the vehicle speed VP during cruisecontrol or not, with reference to the flowcharts.

Firstly, in step S01 shown in FIG. 3, it is determined whether the shiftposition SH of the transmission T detected by the shift position sensorS3 is 5-speed or not.

If this determination is “NO”, the flow proceeds to step S03 describedlater.

On the other hand, if this determination is “YES”, the flow proceeds tostep S02, where a table of the 5-speed cylinder deactivation upper limitENG torque #TQCS 5AH/L having hysteresis which changes according to thevehicle speed VP is retrieved so as to set an NV cylinder deactivationupper limit ENG torque TQCSX having hysteresis (that is, a high NVcylinder deactivation upper limit ENG torque TQCS HX and a low NVcylinder deactivation upper limit ENG torque TQCS LX), and the flowproceeds to step S08 described later. Here, the NV cylinder deactivationupper limit ENG torque TQCSX is, for example the upper limit of ENGtorque for permitting execution of the cylinders deactivation operationin a state where noise, vibration, or the like generated in theinternal-combustion engine E in the cylinders deactivation operatingstate are controlled to under predetermined values.

Moreover, in step S03, it is determined whether the shift position SH ofthe transmission T detected by the shift position sensor S3 is 4-speedor not.

If this determination is “NO”, the flow proceeds to step S05 describedlater.

On the other hand, if this determination is “YES”, the flow proceeds tostep S04, where a table of the 4-speed cylinder deactivation upper limitENG torque #TQCS 4AH/L having hysteresis which changes according to thevehicle speed VP is retrieved so as to set the NV cylinder deactivationupper limit ENG torque TQCSX having hysteresis (that is, the high NVcylinder deactivation upper limit ENG torque TQCS HX and the low NVcylinder deactivation upper limit ENG torque TQCS LX), and the flowproceeds to step S08 described later.

Moreover, step S05, it is determined whether the shift position SH ofthe transmission T detected by the shift position sensor S3 is 3-speedor not.

If this determination is “YES”, the flow proceeds to step S06, where atable of the 3-speed cylinder deactivation upper limit ENG torque #TQCS3AH/L having hysteresis which changes according to the vehicle speed VPis retrieved so as to set the NV cylinder deactivation upper limit ENGtorque TQCSX having hysteresis (that is, the high NV cylinderdeactivation upper limit ENG torque TQCS HX and the low NV cylinderdeactivation upper limit ENG torque TQCS LX), and the flow proceeds tostep S08 described later.

On the other hand, if this determination is “NO”, that is, in the casewhere the shift position SH is 1-speed or 2-speed, the flow proceeds tostep S07, where a table of a 1, 2-speed cylinder deactivation upperlimit ENG torque #TQCS12AH/L having hysteresis which changes accordingto the vehicle speed VP is retrieved so as to set the NV cylinderdeactivation upper limit ENG torque TQCSX having hysteresis (that is,the high NV cylinder deactivation upper limit ENG torque TQCS HX and thelow NV cylinder deactivation upper limit ENG torque TQCS LX), and theflow proceeds to step S08 described later.

Next, in step S08, a value obtained by multiplying the ENG maximumtorque during cylinder deactivation TQE3MAX obtained by correcting themaximum value of ENG torque capable of being output from theinternal-combustion engine E during cylinders deactivation operationaccording to the environment such as atmospheric pressure by, forexample, the predetermined coefficient #KTQM3H, #KTQM3L havinghysteresis for changing to decrease the ENG maximum torque duringcylinder deactivation TQE3MAX based on the magnitude correlation of thefuel consumption efficiency between the all cylinders operation and thecylinders deactivation operation according to the retard amount forsuppressing the knock generation in the internal-combustion engine E(for example, delayed amount of ignition timing), is set to the ENGtorque during cylinder deactivation TQECS having hysteresis (that is,high ENG torque during cylinder deactivation TQECSH, and low torqueduring cylinder deactivation TQECSL).

Next, in step S09, the smaller one of the NV cylinder deactivation upperlimit ENG torque TQCSX having hysteresis according to each shiftposition SH (that is, the high NV cylinder deactivation upper limit ENGtorque TQCS HX and the low NV cylinder deactivation upper limit ENGtorque TQCS LX), and the ENG torque during cylinders deactivation TQECShaving hysteresis (that is, the high ENG torque during cylindersdeactivation TQECSH and the low ENG torque during cylinders deactivationTQECSL), is set to the cylinder deactivation upper limit ENG torque TQCShaving hysteresis (that is, the high cylinder deactivation upper limitENG torque TQCS H and the low cylinder deactivation upper limit ENGtorque TQCS L).

Next, in step S10, a value obtained by adding to the cylinderdeactivation upper limit ENG torque TQCS having hysteresis (that is, thehigh cylinder deactivation upper limit ENG torque TQCS HX and the lowcylinder deactivation upper limit ENG torque TQCS LX), the energymanagement discharge torque limit for cylinder deactivation enlargementassistance TQMLTCSA, being for example the upper limit of the motortorque set corresponding to the energy state in high voltage electricalequipment and the operating state of the vehicle, is set to the cylinderdeactivation upper limit torque TQACS having hysteresis (that is, thehigh cylinder deactivation upper limit torque TQACSH and the lowcylinder deactivation upper limit torque TQACSL).

Next, in step S11 shown in FIG. 4, it is determined whether the flagvalue of an all cylinder region determination flag F_TQCS which showsthat the power plant required torque final value TQPPRQF is in the allcylinder region, is “1” or not.

If this determination is “YES” (all cylinder region and cylinderdeactivation is prohibited), the flow proceeds to step S20 describedlater.

On the other hand, if this determination is “NO” (cylinder deactivationregion), the flow proceeds to step S12.

In step S12, it is determined whether the power plant required torquefinal value TQPPRQF is greater than or equal to the high cylinderdeactivation upper limit torque TQACSH of the cylinder deactivationupper limit torque TQACS having hysteresis or not.

If the determination in step S12 is “YES”, the flow proceeds to step S14described later.

On the other hand, if the determination in step S12 is “NO”, the flowproceeds to step S13, where, the power plant required torque final valueTQPPRQF during cruise control, is set to a predetermined torque value,and for example a “0” is set to the flag value of the torque hold flagF_CCKTQS showing to hold for example to the torque value equivalent tothe high cylinder deactivation upper limit torque TQACSH of the cylinderdeactivation upper limit torque TQACS having hysteresis, and the seriesof processing is then terminated.

Moreover, in step S14, a predetermined time value #TMTQCSDL which is thedelay time when switching the flag value of the all cylinder regiondetermination flag F_TQCS from “1” to “0” is set to a delay timeTTQCSDL.

Moreover, in step S15, it is determined whether the flag value of acruise control determination flag F_TQCC which shows that the vehicle istraveling under cruise control, is “1” or not.

If this determination is “NO”, the flow proceeds to step S16, where a“1” is set to the flag value of the all cylinder region determinationflag F_TQCS , and the flow proceeds to step S13 described later.

On the other hand, if this determination is “YES” (auto-cruisetravelling), the flow proceeds to step S17.

In step S17, a table of a torque addition term #DTQCCCSN which variesaccording to the vehicle speed is retrieved, and a torque addition termDTQCCCSX is set, and a value obtained by adding this torque additionterm DTQCCCSX to the high cylinder deactivation upper limit torqueTQACSH of the cylinder deactivation upper limit torque TQACS havinghysteresis is set to the cylinder deactivation upper limit torque duringcruise control, TQCCACS.

Moreover, in step S 18, it is determined whether the power plantrequired torque final value TQPPRQF is greater than or equal to acylinder deactivation upper limit torque during cruise control TQCCACSor not.

If the determination in step S18 is “YES”, the flow proceeds to step S16described above.

On the other hand, if the determination in step S18 is “NO”, the flowproceeds to step S19, where a “1” is set to the flag value of the torquehold flag F_CCKTQS, and the series of processing is terminated.

The torque addition term DTQCCCSX in step S17 described above is, forexample, for keeping the flag value of the torque hold flag F_CCKTQSfrom fluctuating due to fluctuations in the power plant required torquefinal value TQPPRQF due to noise or the like.

Moreover, in step S20, it is determined whether the power plant requiredtorque final value TQPPRQF is greater than or equal to the low cylinderdeactivation upper limit torque TQACSL of the cylinder deactivationupper limit torque TQACS having hysteresis or not.

If this determination is “NO”, the flow proceeds to step S21, where a“0” is set to the flag value of the all cylinder region determinationflag F_TQCS, and the flow proceeds to step S13 described above.

On the other hand, if this determination is “YES”, the flow proceeds tostep S22.

In step S22, it is determined whether the power plant required torquefinal value TQPPRQF is less than or equal to the high cylinderdeactivation upper limit torque TQACSH of the cylinder deactivationupper limit torque TQACS having hysteresis or not.

If the determination in step S22 is “NO”, the flow proceeds to step S21,where a “0” is set to the flag value of the all cylinder regiondetermination flag F_TQCS, and the flow proceeds to step S13 describedabove.

On the other hand, if this determination is “YES”, the flow proceeds tostep S23, where a predetermined time value #TMTQCSDL which is the delaytime when switching the flag value of the all cylinder regiondetermination flag F_TQCS from “1” to “0” is set to the delay timeTTQCSDL, and the series of processing is terminated.

Moreover, in step S24, it is determined whether the time value of thedelay time TTQCSDL is zero or not.

If this determination is “YES”, the flow proceeds to step S21 describedabove.

On the other hand if this determination is “NO”, the flow proceeds tostep S13 described above.

That is, the arrangement is such that, the flag value of the allcylinder region determination flag F_TQCS is switched from “1” to “0”according to the time value of the delay time TTQCSDL so as to suppressthe generation of hunting which frequently switches between the allcylinders operation and the cylinders deactivation operation, and evenif the power plant required torque final value TQPPRQF is greater thanthe low cylinder deactivation upper limit torque TQACSL, the cylindersdeactivation operation is permitted so as to improve the fuelconsumption efficiency.

Hereunder is a description of processing of the cylinder deactivationcontrol based on the flag value of the torque hold flag F_CCKTQS, withreference to the flowcharts.

Firstly, in step S31 shown in FIG. 5, it is determined whether the flagvalue of the all cylinder region determination flag F_TQCS which showsthe power plant required torque final value TQPPRQF is in the allcylinders operation region, is “0” or not.

If this determination is “NO” (all cylinder region, with cylinderdeactivation prohibited), the flow proceeds to step S32, where a “0” isset to the flag value of a cylinder deactivation request flag F_CSCMDwhich requests execution of the cylinders deactivation operation for theinternal-combustion engine E, and the operating state of theinternal-combustion engine E is switched from the cylinders deactivationoperation to the all cylinders operation, and the series of processingare terminated.

On the other hand, if this determination is “YES” (cylinder deactivationregion), the flow proceeds to step S33.

In step S33, it is determined whether the flag value of the torque holdflag F_CCKTQS is “1” or not.

If the determination in step S33 is “NO”, the flow proceeds to step S34,where a “1” is set to the flag value of the cylinder deactivationrequest flag F_CSCMD which requests execution of the cylindersdeactivation operation for the internal-combustion engine E, and theseries of processing is terminated.

On the other hand, if the determination in step S33 is “YES”, the flowproceeds to step S35.

In step S35, it is determined whether the vehicle speed VP is less thana value obtained by subtracting from the set vehicle speed VC which isthe target vehicle speed during cruise control, a predetermined vehiclespeed #ΔV (for example, #ΔV=3 km/h or the like) or not.

If the determination in step S35 is “YES”, the flow proceeds to step S32described above.

On the other hand, if the determination in step S35 is “NO”, the flowproceeds to step S36.

Moreover, in step S36, it is determined whether a “1” is set to the flagvalue of a flag F_WOT which shows switching from the stoichiometricstate to the rich side state in the A/F (air/fuel ratio) control of theair-fuel mixture supplied to the internal-combustion engine E, or not.

If this determination is “YES”, that is, in the case where there is arequirement for switching from the stoichiometric state to the rich sidestate with respect to the air/fuel ratio, it is determined that theprocessing for continuing the cylinders deactivation operation isunnecessary, and the flow proceeds to step S32 described above.

On the other hand, if this determination is “NO”, the flow proceeds tostep S37.

In step S37, it is determined whether a “1” is set to the flag value ofa flag F_ATREQ which instructs to prohibit execution of the cylinderdeactivation, in order to suppress the generation of torque fluctuationsat the time of the shift operation of the automatic transmission (AT) orthe like, or not.

If the determination in step S37 is “YES”, that is, in the case wherethe instruction is to prohibit execution of the cylinder deactivationrelated to the shift operation of the automatic transmission (AT), theflow proceeds to step S32 described above.

On the other hand, if the determination in step S37 is “NO”, the flowproceeds to step S38.

In step S38, it is determined whether a “1” is set to the flag value ofa flag F_CSCATCND which shows that a temperature TCAT of a catalyst forpurifying HC, CO, NO_(x) and the like in the exhaust gas is, for examplewithin a predetermined temperature range greater than a predeterminedactivation temperature and less than a predetermined upper limittemperature, or not.

If this determination “NO”, that is, in the case where the temperatureTCAT of the catalyst is out of the predetermined temperature range, theflow proceeds to step S32 described above.

On the other hand, if this determination is “YES”, the flow proceeds tostep S39.

In step S39, it is determined whether a “1” is set to the flag value ofa flag F_CSOILCMD which shows, for example that the duration of thecylinders deactivation operation exceeds a predetermined duration, ornot.

If the determination in step S39 is “YES”, it is determined that due forexample to the duration of the cylinders deactivation operationexceeding the predetermined duration, there is a likelihood of adecrease in the operating oil in a bank on one side, in the state wherethree cylinders are deactivated, and the flow proceeds to step S32described above.

On the other hand, if the determination in step S39 is “NO”, the flowproceeds to step S40.

In step S40, it is determined whether or not a “1” is set to the flagvalue of a flag F_CS36INT which instructs to switch from the cylindersdeactivation operation to the all cylinders operation, corresponding toan over decrease in the engine rotating speed NE due for example torapid deceleration or the like.

If the determination in step S40 is “YES”, the flow proceeds to step S32described above.

On the other hand, if the determination in step S40 is “NO”, the flowproceeds to step S34 described above.

That is, in a state where the cylinders deactivation operation of theinternal-combustion engine E is executed during cruise control forconstant speed traveling which controls the internal-combustion engine Eand the motor M so that the vehicle speed VP becomes a predetermined setvehicle speed VC, then for example, if the vehicle path become agradient such as after time t1 shown in FIG. 6, the vehicle speed VPchanges in a decreasing trend and the power plant required torque finalvalue TQPPRQF which is the target torque for the torque output from thepower plant changes in an increasing trend.

Moreover, for example similarly to the period after time t2 shown inFIG. 6, if the power plant required torque final value TQPPRQF becomesgreater than the cylinder deactivation upper limit ENG torque TQCS whichis the ENG torque capable of being output from the internal-combustionengine E during the cylinders deactivation operation (for example, thelow cylinder deactivation upper limit ENG torque TQCSL of the cylinderdeactivation upper limit ENG torque TQCS having hysteresis), the torquevalue of the difference between the power plant required torque finalvalue TQPPRQF and the cylinder deactivation upper limit ENG torque TQCSis set to the motor required torque, and the cylinder deactivation upperlimit ENG torque TQCS is set to the engine required torque, and as aresult, the period becomes the cylinder deactivation enlargementassistance region to continue the cylinders deactivation operatingstate.

Furthermore, in this cylinder deactivation enlargement assistanceregion, the FI/AT/MGECU 36, for example similarly to the period aftertime t3 shown in FIG. 6, even in a case where, with a further increasein the vehicle path gradient and the vehicle speed VP further changingin the decreasing trend, the torque required for the vehicle speed VP tofollow the predetermined set vehicle speed VC is increased, in the casewhere the vehicle speed VP is greater than a value obtained bysubtracting from the set vehicle speed VC, the predetermined vehiclespeed #ΔV (for example, #ΔV=3 km/h or the like), the power plantrequired torque final value TQPPRQF is controlled not to increase abovea predetermined torque value, for example a torque value equivalent tothe high cylinder deactivation upper limit torque TQACSH of the cylinderdeactivation upper limit torque TQACS having hysteresis, and the powerplant required torque final value TQPPRQF is held to a predeterminedtorque value, for example a torque value equivalent to the high cylinderdeactivation upper limit torque TQACSH.

At this time, in the case where, for example the driver required valueexceeds the C/C required torque due to rapid acceleration according tothe accelerator pedal operation of the driver, the flag value of thecruise control determination flag F_TQCC becomes a “0” so that thedetermination in step S15 described above becomes “NO”, and the powerplant required torque final value TQPPRQF is not held to thepredetermined torque value, and as a result, the power plant requiredtorque final value TQPPRQF becomes in the all cylinders operating state,at the point in time for example when the high cylinder deactivationupper limit torque TQACSH of the cylinder deactivation upper limittorque TQACS having hysteresis is exceeded.

Moreover, for example similarly to the time t4 shown in FIG. 6, at thepoint in time when the vehicle speed VP becomes less than a valueobtained by subtracting from the set vehicle speed VC the predeterminedvehicle speed #ΔV (for example, #ΔV=3 km/h or the like), then similarlyto step S32 described above, a “0” is set to the flag value of thecylinder deactivation request flag F_CSCMD which requests execution ofthe cylinders deactivation operation for the internal-combustion engineE, and a “1” is set to the flag value of the all cylinders required flagwhich instructs to set the operating state of the internal-combustionengine E to the all cylinders operation during cruise control.Accompanying this, at the point in time when a predetermined controldelay time Δtd1 has passed from the time t4, the internal-combustionengine E is actually switched from the cylinders deactivation operationto the all cylinders operation, and further, a “1” is set to the flagvalue of a FI all cylinders determination flag which determines theoperating state of the internal-combustion engine E, according towhether the power plant required torque final value TQPPRQF is greaterthan the cylinder deactivation upper limit torque TQACS or not.

Here, during the period from t4 when a “1” is set to the flag value ofthe CC all cylinders required flag to t5 when the predetermined durationΔtc1 has passed, by continuing the state of torque hold which holds thepower plant required torque final value TQPPRQF to the predeterminedtorque value, for example a torque value equivalent to the high cylinderdeactivation upper limit torque TQACSH, then rapid torque fluctuationcan be kept from being generated when switching the internal-combustionengine E from the cylinders deactivation operation to the all cylindersoperation.

Furthermore, for example similarly to the period after time t5 shown inFIG. 6, the state of torque hold is cancelled, and accompanying anincrease in the power plant required torque final value TQPPRQF so thatthe vehicle speed VP follows the predetermined set vehicle speed VC, thedifference between the vehicle speed VP and the predetermined setvehicle speed VC changes in a decreasing trend. Then, when thedifference between the vehicle speed VP and the predetermined setvehicle speed VC becomes less than a predetermined difference, the powerplant required torque final value TQPPRQF changes in a decreasing trend.

Here, for example similarly to the period after time t5 shown in FIG. 6,since the power plant required torque final value TQPPRQF becomes lessthan, for example the low cylinder deactivation upper limit torqueTQACSL of the cylinder deactivation upper limit torque TQACS havinghysteresis, then even in a case where a “0” is set to the flag value ofthe FI all cylinders determination flag, the FI/AT/MGECU 36 continuesthe state where a “1” is set to the flag value of the CC all cylindersrequired flag, that is where a “0” is set to the flag value of thecylinder deactivation request flag F_CSCMD, and continues the actualoperating state of the internal-combustion engine E being in the allcylinders operation. Therefore, the vehicle speed VP becomes a stablevalue to follow the predetermined set vehicle speed VC, and the powerplant required torque final value TQPPRQF becomes stable at a value lessthan, for example the cylinder deactivation upper limit ENG torque TQCS.

That is, in the period after time t6 shown in FIG. 6, for example if theactual operating state of the internal-combustion engine E is switchedfrom the all cylinders operation to the cylinders deactivation operationaccording to the change in the flag value of the FI all cylindersdetermination flag, then in the vehicle speed VP and the power plantrequired torque final value TQPPRQF, for example as shown by the brokenline Ve and the broken line Trq shown in FIG. 6, hunting occurs whichfluctuates repeatedly at a relatively large rise and fall, and with thisthe actual operating state of the internal-combustion engine E isfrequently switched between the all cylinders operation and thecylinders deactivation operation. To counter this, as described above,in the state where a “1” is set to the flag value of the CC allcylinders required flag, that is a “0” is set to the flag value of thecylinder deactivation request flag F_CSCMD, the FI/AT/MGECU 36 continuesthe actual operating state of the internal-combustion engine E in thestate of all cylinders operation, so as to prevent the occurrence ofhunting.

As described above, according to the control apparatus for a hybridvehicle according to the present embodiment, even if the case where thepower plant required torque final value TQPPRQF becomes greater than thecylinder deactivation upper limit torque TQACS, by allowing decelerationto a level where occupants in the vehicle can not feel discomfort, thecylinders deactivation operation can be continued and the timing forswitching from the cylinders deactivation operation to the all cylindersoperation can be delayed, so that fuel consumption efficiency can beimproved.

Moreover, it is possible to suppress the occurrence of hunting whereswitching between the all cylinders operation and the cylindersdeactivation operation is frequently repeated, so that the occupants inthe vehicle can be kept from feeling discomfort with respect totravelling behavior.

In the embodiment described above, in step S32, the arrangement is suchas to set a “0” to the flag value of the cylinder deactivation requestflag F_CSCMD so as to switch the operating state of theinternal-combustion engine E from the cylinders deactivation operationto the all cylinders operation. However, the arrangement is not limitedto this, and it may be for example so as to set the fuel supply torestart for some of the cylinders in the deactivating state, instead ofswitching to the all cylinders operation.

In the embodiment described above, the arrangement is such that theenergy management discharge torque limit for the cylinder deactivationenlargement assistance TQMLTCSA which is the upper limit of the motortorque, is a predetermined fixed value set according to, for example theenergy state in high voltage electrical equipment or the operating stateof vehicle. However, the arrangement is not limited to this, and forexample as a modified example of the embodiment described above, theenergy management discharge torque limit for cylinder deactivationenlargement assistance TQMLTCSA which is the upper value of the motortorque, may be changed according to the state of charge QBAT of thebattery 3.

In this modified example, for example as shown in FIG. 7, in theprocessing which sets the flag value of the torque hold flag F_CCKTQSshowing whether it is possible to execute the torque hold processingwhich enlarges the cylinders deactivation operation region with respectto the vehicle speed VP during cruise control or not, the processing ofstep S51 is executed between the processing of step S09 and theprocessing of step S10 in the embodiment described above.

In this step S51, for example a table # TQMLTCSA of the energymanagement discharge torque limit for cylinder deactivation enlargementassistance TQMLTCSA which changes in an increasing trend with anincrease in the state of charge QBAT of the battery 3 detected by theHVECU 35, is retrieved so as to set the energy management dischargetorque limit for cylinder deactivation enlargement assistance TQMLTCSAaccording to the detected state of charge QBAT.

That is, in the state of the cylinder deactivation enlargementassistance region which is the state where the cylinders deactivationoperation of the internal-combustion engine E is executed during cruisecontrol for constant travelling which controls the internal-combustionengine E and the motor M so that the vehicle speed VP becomes apredetermined set vehicle speed VC, and further the power plant requiredtorque final value TQPPRQF becomes greater then the cylinderdeactivation upper limit ENG torque TQCS which is the ENG torque capableof being output from the internal-combustion engine E during thecylinders deactivation operation (for example, the low cylinderdeactivation upper limit ENG torque TQCSL of the cylinder deactivationupper limit ENG torque TQCS having hysteresis), and the torque value ofthe difference between the power plant required torque final valueTQPPRQF and the cylinder deactivation upper limit ENG torque TQCS is setto the motor required torque, and the cylinder deactivation upper limitENG torque TQCS is set to the engine required torque so as to continuethe cylinders deactivation operating state, then similarly to the periodafter time t11 shown in FIG. 8, if the vehicle path is a gradient, thevehicle speed VP changes in a decreasing trend and the power plantrequired torque final value TQPPRQF which is the target torque for thetorque output from the power plant changes in an increasing trend.Furthermore, at this time, by driving the motor M by the power supplyfrom the battery 3, the state of charge QBAT of the battery 3 changes ina decreasing trend, and according to this state of charge QBAT, theenergy management discharge torque limit for cylinder deactivationenlargement assistance TQMLTCSA, the cylinder deactivation upper limittorque TQACS, and the cylinder deactivation upper limit torque duringcruise control TQCCACS change in a decreasing trend.

Furthermore, in this cylinder deactivation enlargement assistanceregion, the FI/AT/MGECU 36, for example similarly to the period aftertime t11 shown in FIG. 8, even in a case where, with a further increasein the vehicle path gradient and the vehicle speed VP further changingin the decreasing trend, the torque required for the vehicle speed VP tofollow the predetermined set vehicle speed VC is increased, in the casewhere the vehicle speed VP is greater than a value obtained bysubtracting from the set vehicle speed VC, the predetermined vehiclespeed #ΔV (for example, #ΔV=3 km/h or the like), the power plantrequired torque final value TQPPRQF is controlled not to increase abovea predetermined torque value, for example a torque value equivalent tothe high cylinder deactivation upper limit torque TQACSH of the cylinderdeactivation upper limit torque TQACS having hysteresis, and the powerplant required torque final value TQPPRQF is held to a predeterminedtorque value, for example a torque value equivalent to the high cylinderdeactivation upper limit torque TQACSH.

Here, as the cylinder deactivation upper limit torque TQACS changes in adecreasing trend, the power plant required torque final value TQPPRQFchanges in a decreasing trend.

Moreover, for example similarly to the period after time t13 shown inFIG. 8, at the point in time when the gradient of the vehicle path isfurther increased and the vehicle speed VP further changes in adecreasing trend, and similarly to the time t14 shown in FIG. 8, thevehicle speed VP becomes less than a value obtained by subtracting fromthe set vehicle speed VC a predetermined vehicle speed #ΔV (for example,#ΔV=3 km/h or the like), similarly to the step S32 described above, a“0” is set to the flag value of the cylinder deactivation request flagF_CSCMD which requests execution of the cylinders deactivation operationfor the internal-combustion engine E, and a “1” is set to the flag valueof the all cylinders required flag which instructs to set the operatingstate of the internal-combustion engine E to the all cylinders operationduring cruise control. Accompanying this, at the point in time when apredetermined control delay time Δtd1 has passed from the time t14, theinternal-combustion engine E is actually switched from the cylindersdeactivation operation to the all cylinders operation, and further a “1”is set to the flag value of the FI all cylinders determination flagwhich determines the operating state of the internal-combustion engineE, according to whether the power plant required torque final valueTQPPRQF is greater than the cylinder deactivation upper limit torqueTQACS or not.

Furthermore, for example similarly to the period after time t14 shown inFIG. 8, the state of torque hold is cancelled, and accompanying anincrease in the power plant required torque final value TQPPRQF so thatthe vehicle speed VP follows the predetermined set vehicle speed VC, anincrease in the difference between the vehicle speed VP and thepredetermined set vehicle speed VC is suppressed. With the change ofthis difference in a decreasing trend, the power plant required torquefinal value TQPPRQF changes in a decreasing trend.

Here, for example similarly to the period after time t15 shown in FIG.8, even in the case where the power plant required torque final valueTQPPRQF becomes less than, for example the low cylinder deactivationupper limit torque TQACSL of the cylinder deactivation upper limittorque TQACS having hysteresis, the FI/AT/MGECU 36 continues the statewhere a “1” is set to the flag value of the CC all cylinders requiredflag, that is where a “0” is set to the flag value of the cylinderdeactivation request flag F_CSCMD, and continues the actual operatingstate of the internal-combustion engine E being in the all cylindersoperation.

That is, in the period after time t12 shown in FIG. 8, for example, if apredetermined value is set to the energy management discharge torquelimit for cylinder deactivation enlargement assistance TQMLTCSAirrespective of the state of charge QBAT of the battery 3 which changesin a decreasing trend, the cylinder deactivation upper limit torqueTQACS and the deactivation upper limit torque during cruise controlTQCCACS based on this energy management discharge torque limit forcylinder deactivation enlargement assistance TQMLTCSA becomes unchangedregardless of the change of the state of charge QBAT. Accompanying this,for example as shown by the broken line Trq shown in FIG. 8, the powerplant required torque final value TQPPRQF becomes unchanged regardlessof the change in the state of charge QBAT. However, accompanying thechange in the state of charge QBAT in the actual battery 3 in adecreasing trend, the actual cylinder deactivation upper limit torqueTQACS and the cylinder deactivation upper limit torque during cruisecontrol TQCCACS change in a decreasing trend. Therefore, for examplesimilarly to time t13 shown in FIG. 8, as shown by the broken line Trq,the power plant required torque final value TQPPRQF reaches to theactual cylinder deactivation upper limit torque during cruise controlTQCCACS, and as a result, it is determined by the FI/AT/MGECU 36 that itis difficult to continue the state of the cylinder deactivationenlargement assistance region. Therefore, according to whether the powerplant required torque final value TQPPRQF becomes more than the cylinderdeactivation upper limit torque TQACS or not, a “1” is set to the flagvalue of the FI all cylinders determination flag which determines theoperating state of the internal-combustion engine E, and theinternal-combustion engine E is actually switched from the cylindersdeactivation operation to the all cylinders operation , and a “1” is setto the flag value of the CC all cylinders required flag at the point intime when a suitable control delay time Δtd2 has passed from the timet13. That is, in the state of the cylinder deactivation enlargementassistance region, at a timing prior reaching the time t14 when thevehicle speed VP becomes less than a value obtained by subtracting fromthe set vehicle speed VC a predetermined vehicle speed #ΔV (for example,#ΔV=3 km/h or the like), the processing of the cylinder deactivationenlargement assistance is cancelled. To counter this, as with themodified example described above, by calculating the energy managementdischarge torque limit for cylinder deactivation enlargement assistanceTQMLTCSA according to the state of charge QBAT of the battery 3, theprocessing of the cylinder deactivation enlargement assistance can beappropriately continued.

In the modified example described above, in the processing which setsthe flag value of the cylinder deactivation request flag F_CSCMD whichrequests execution of the cylinders deactivation operation for theinternal-combustion engine E, then for example as shown in FIG. 9,instead of the torque hold flag F_CCKTQS in the embodiment describedabove, according to the flag value of an all cylinders instruction flagduring cruise control F_CCKZ1 which instructs to set the operating stateof the internal-combustion engine E to the all cylinders operationduring cruise control, the processing for the cylinder deactivationcontrol may be executed. In this case, instead of the processing in stepS33 in the embodiment described above, the processing in step S52 isexecuted.

In this step S52, it is determined whether the flag value of the allcylinders instruction flag during cruise control F_CCKZ1 is “1” or not.

If this determination is “YES”, the flow proceeds to step S32.

On the other hand, if this determination is “NO”, the flow proceeds tostep S35.

As described above, according to the control apparatus for a hybridvehicle of the present invention, even in the case where the targettorque for the power plant torque exceeds for example the cylinderdeactivation upper limit torque, by allowing deceleration to a levelwhere occupants in the vehicle can not feel discomfort, the cylindersdeactivation operation can be continued and the timing for switchingfrom the cylinders deactivation operation to the all cylinders operationcan be delayed, so that fuel consumption efficiency can be improved.

Furthermore, according to the control apparatus for a hybrid vehicle ofthe present invention, it is possible to generate a driving forceunerringly reflecting the driver's intention to accelerate at anappropriate timing.

Moreover, according to the control apparatus for a hybrid vehicle of thepresent invention, it is possible to control the operating state of theinternal-combustion engine appropriately and flexibly according to thestate of the vehicle.

Furthermore, according to the control apparatus for a hybrid vehicle ofthe present invention, it is possible to suppress the occurrence ofhunting where canceling and releasing of canceling of the fuel supply isalternatively repeated, and it is possible to keep occupants in thevehicle from feeling discomfort with respect to the traveling behavior.

Furthermore, according to the control apparatus for a hybrid vehicle ofthe present invention, it is possible to appropriately continueprocessing of the cylinder deactivation enlargement assistance.

While preferred embodiments of the invention have been described andillustrated above, it should be understood that these are exemplary ofthe invention and are not to be considered as limiting. Additions,omissions, substitutions, and other modifications can be made withoutdeparting from the spirit or scope of the present invention.Accordingly, the invention is not to be considered as being limited bythe foregoing description, and is only limited by the scope of theappended claims.

1. A control apparatus for a hybrid vehicle which includes: a variablecylinder internal-combustion engine capable of switching between an allcylinders operation which operates all cylinders and a cylindersdeactivation operation which operates with some cylinders deactivated,and a motor as a power source; and a power storage unit which transferselectric energy with said motor, and at least one of said variablecylinder internal-combustion engine and said motor is connected todriving wheels of the vehicle through a transmission so as to transmit adriving force to said driving wheels, wherein said control apparatuscomprises: a fuel supply canceling device which cancels fuel supply tosaid some cylinders according to an operating state of the vehicle; acruise control device which controls at least one of a cruise control totravel drive the vehicle so that the vehicle speed follows apredetermined target speed, and a cruise control to make said vehicletravel while maintaining a predetermined vehicular gap with respect to apreceding vehicle; an upper limit engine torque calculating device whichcalculates an upper limit value of an engine torque capable of beingoutput from said variable cylinder internal-combustion engine duringsaid cylinders deactivation operation; an upper limit motor torquecalculating device which calculates an upper limit value of motor torquecapable of being output from said motor during an assisting operationwhich assists the output of said variable cylinders internal-combustionengine by the output from said motor; a torque limiting device whichlimits a target torque for a power plant torque capable of being outputfrom a power plant comprising said variable cylinder internal-combustionengine and said motor during operation of said fuel supply cancelingdevice and said cruise control to under a value equivalent to apredetermined torque related to a cylinder deactivation upper limittorque obtained by adding an upper limit value of said engine torque andan upper limit value of said motor torque; and a fuel supply cancelreleasing device which releases cancellation of the fuel supply to atleast some of the cylinders among said cylinders to which the fuelsupply is cancelled by said fuel supply canceling device, when saidvehicle speed is decreased under a speed obtained by subtracting fromsaid target speed, a predetermined speed during operation of said torquelimiting device.
 2. A control apparatus for a hybrid vehicle accordingto claim 1, wherein said fuel supply cancel releasing device cancels theoperation of said fuel supply canceling device to thereby switch theoperating state of said variable cylinder internal-combustion enginefrom the cylinders deactivation operation to the all cylindersoperation.
 3. A control apparatus for a hybrid vehicle according toclaim 1, wherein said fuel supply canceling device, in at least one caseof: a case where the air/fuel ratio of an air-fuel mixture supplied tosaid variable cylinder internal-combustion engine is changed from atheoretical air/fuel ratio to a rich side state; a case where a shiftoperation is executed in said transmission; a case where a temperatureof a catalyst which purifies exhaust gas of said variable cylinderinternal-combustion engine departs from a predetermined activationtemperature range; a case where a duration of said cylindersdeactivation operation exceeds a predetermined duration; and a casewhere a rotating speed of said variable cylinder internal-combustionengine is decreased to under a predetermined rotating speed, releasesthe cancellation of the fuel supply to at least some of the cylindersamong said cylinders to which the fuel supply is cancelled by said fuelsupply canceling device.
 4. A control apparatus for a hybrid vehicleaccording to claim 1, further comprising: a fuel supply cancelprohibiting device which, after said fuel supply cancel releasing devicereleases the cancellation of the fuel supply to at least some of thecylinders among said cylinders to which the fuel supply is cancelled bysaid fuel supply canceling device, prohibits execution of thecancellation of fuel supply to said at least some of the cylinders towhich the cancellation of the fuel supply is released by said fuelsupply cancel releasing device.
 5. A control apparatus for a hybridvehicle according to claim 1, wherein said upper limit value of motortorque is calculated according to a state of charge of said powerstorage unit.